Flat valve for hydraulic motor



June 5, 1962 w. G. DOUGLAS 3,037,489

FLAT VALVE FOR HYDRAULIC MOTOR Filed May 5, 1960 2 Sheets-Sheet 1 IRS ! INVENTOR 1 WILL/AM a 00062 A5 I ATTORNEY June 5., 1962 Filed May 5, 1960 W. G. DOUGLAS FLAT VALVE FOR HYDRAULIC MOTOR 2 Sheets-Sheet 2 INVENTOR WILL/AM 62 DOUGLAS ATTORNEY United States Patent 3,037,489 FLAT VALVE FOR HYDRAULIC MOTOR William G. Douglas, Whitefish Bay, Wis., assignor to The Oilgear Company, Milwaukee, Wis. Filed May 5, 1960, Ser. No. 27,131 7 Claims. (Cl. 121-62) This invention relates to rotary hydrodynamic machines in which pistons and cylinders are arranged in a cylinder barrel and the pistons reciprocate 'as the cylinder barrel rotates. The flow of liquid to and from the cylinders is controlled by a floating flat valve that has a pair of areaate ports without which the cylinder ports alternately register. More particularly the invention relates to timing of the energization and deenergization of auxiliary hold up motors provided in bridges of the valve.

The hydrodynamic machine has a rotary cylinder barrel, and fluid flow to and from cylinder ports therein is valved by a non-rotatable and axial floating type of flatvalve in the manner illustrated in U.S. Patent 2,406,138 assigned to the assignee of this application.

Auxiliary hold-11p motors heretofore were not simultaneously energized and simultaneously deenergized upon alternating the number of cylinder ports registering with the pressure one of the valve ports, and the auxiliary holdup motors, moreover, trapped pressure fluid therein for a substantial interval of cylinder barrel rotation after such auxiliary motors should have been connected to exhaust. The flat valve also was subject to hold-up forces whose centroid was supposed to follow the centroid of the blow off forces between the cylinder barrel and the flat valve.

The present invention is well suited for operation of the motor at slow speeds as well as at higher speeds. The auxiliary hold-up motors are simultaneously energized whenever a greater number of cylinder ports register with the valve pressure port and are simultaneously deenergized whenever a greater number of cylinder ports register with the valve exhaust port.

According to the present invention, and an object therei of, the auxiliary hold-up motors under both bridges of the flat valve are energized and maintained energized when an even number of cylinder ports are in communication with the pressure port of the flat valve and these auxiliary hold-up motors under both bridges are deenergized and maintained deenergized when an odd number of cylinder ports are in communication with the pressure port of the flat valve, when the total number of cylinder ports is odd.

It is also an object of the present invention to provide means in the face of the flat valve that cooperates with the cylinder ports to simultaneously energize and alternately to simultaneously deenergize the hold-up motors under both bridges of the flat valve.

Another object of the invention is to provide a hydraulic motor having a rotating cylinder barrel having an odd number of reciprocating pistons with a flat valve having hold-up motors under port and bridge portions of the flat valve, with slots in the face of the bridges to extend the time that the hold-up motors under both bridges are energized to a period substantially equivalent to one-half the angular spacing between cylinder ports.

Another object of the invention is to energize and to deenergize the hold-up motors under both bridges of a flat valve simultaneously with the cylinder ports in communication with the pressure port of the valve changing, respectively, to a larger number and then to a fewer number.

Another object of the invention is to provide a floating type fiat valve that will always have the hold up motors under both its bridges energized whenever a greater number of cylinder ports are in communication with a pressure port of the valve so that such hydraulic motor 3,037,489 Patented June 5, 1962 "Ice.

may properly operate under load at relatively slow speeds.

Other objects and advantages of the invention will be apparent on reading the following description with the accompanying drawings, in which:

FIG. 1 is a view in elevation and partially in section of a hydraulic motor embodying the present invention;

FIG. 2 is a view taken on line 2--'2 of FIG. 1 to show only the operating face of the flat valve with the relative position of opposing cylinder ports indicated thereon;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2 and also showing part of the support structure for the flat valve;

FIG. 4 is a sectional view taken along the line 44 of FIG. 2;

FIG. 5, FIG. 6 and FIG. 7 are similar views of the valve plate shown in FIG. 2 but with the opposing cylinder ports indicated in different rotative positions of distribution thereon.

The motor may be a variable displacement motor or a constant displacement motor having a rotatable cylinder barrel with radially or axially arranged pistons. The motor 10 shown is a fixed displacement axial piston type and comprises an angular shaped casing. A shaft 12 adapted for coupling to a load device has a. drive flange 13 mounted for rotation with the shaft in section 11 of the casing. The shaft 12 and flange 16 are suitably rotatably supported on radial and thrust bearings, not shown, in casing section 11.

A cylinder barrel 14 is rotatably supported on axially spaced bearings 16, 17 disposed on an axially extending stud 18 in the end head 19 of the casing section 21. The bearings 16, 17 hold the cylinder barrel against axial and radial displacement. The axes of shaft 12 and of cylinder barrel 14 are inclined relative to each other to provide the fixed displacement for the motor. The cylinder barrel 1:4 is provided with a plurality of cylinders 22 parallel with its axis and has axially reciprocable pistons 23 therein. The pistons 23 are connected to the drive flange 13 by piston rods 24 whose ends are held in ball sockets in the drive flange 13. The cylinder barrel is provided with an odd number of N cylinders herein shown with seven cylinders. The shaft is linked to the cylinder barrel by a constant velocity coupling 26 such as a Cardan shaft which couples a pair of universal joints in the axis of the shaft and in the axis of the cylinder barrel.

The cylinders 22 provide N cylinder ports 29 in the end face of the cylinder barrel and each alternately registers with a supply port 31 and an exhaust port 32 of a flat valve 33 as the cylinder barrel rotates. The ports 31, 32 are diametrically arranged arcuate slots in the front or cylinder opposing face of the flat valve. Axial passages 34 in the flat valve extend through hollow pistons 45 of hold-up motors 42 and connect port 31 with axial passages 35 in the head 19 and these join common manifold passage 36 which terminates in an outer 'connection 37 which may be either a supply or discharge connection for the motor.

Axial passages 38 in the flat valve extend through hollow pistons 45 of hold-up motors 43 and connect port 32 to aligned axial passages 39 in end head 19 which join a common manifold passage 40 that terminates in the other outer connection 41. Fluid supply entering outer connection 37 flows through manifold passage 36, thence through axial passages 35 and aligned passages 34 in the flat valve to its relatively high pressure or supply port 31. Cylinder ports 29 registering with valve supply port 31 receive pressure fluid'therefrom to displace their pistons. Cylinder ports registering with the relatively low pressure or discharge port 32 of the valve discharge their fluid thereto which fluid flows through axial passages 38 in the flat valve and aligned axial passages 39 in end head 19 to manifold passage 40 and to discharge connection 41."

The fiat valve 33 is annular and is disposed coaxially of the stub shaft 18 and of the cylinder barrel. The flat valve is secured on the end head against rotation and for freedom of axial movement. The flat valve is hydraulically balanced between the cylinder barrel and the end head by a hold-up system which produces hold-up forces acting between the valve and the end head which are equal and opposite to the separating forces produced by the pressures between the cylinder barrel and the fiat valve.

The hold-up system comprises hold-up motors 42, 43 and auxiliary motors 47, 48 located in the bridges of the valve which are the portions between the arcuate ports 31, 32. The hold-up motors 42, 43 comprise cylinders 44 always connected to their respective ports 31, 32 and have hollow pistons 45 for connecting the valve ports to the end head passages.

Springs 46 urge the pistons 45 in seating engagement with the aligned passages 35, 39 in the end head. The hold-up motors 42 are three in number and are arranged relative to their associated valve port 31 to provide a hold-up force equal and opposite the separating force developed when an odd number, /2 of (N1), cylinder ports register with and are evenly distributed on valve port 31. Hold-up motors 43 are similarly arranged relative to valve port 32 as hold-up motors 42 to valve port 31. The centroid of the hold-up force due to hold-up motors 42 lies on a transverse axis which lies on section line 3-3 and which is a diametrical line bisecting the ports 31, 32, FIG. 2.

According to this hold-up system the hold-up forces applied by the hold-up motors 42 or 43 are sufiicient to hold the valve balanced against the separating force developed when three cylinder ports register with the supply port of the valve but are insutficient to prevent separation when four cylinder ports register with the supply port. In this manner an excessive hold-up force is not applied when three cylinder ports register with the pressure port and wear between the cylinder barrel or a wear plate 30 thereon and the valve is avoided.

The auxiliary hold-up motors 47, 48 provide additional hold-up force only when four cylinder ports, /2 (N +1), cylinder ports, communicate with the pressure port of the valve. Auxiliary hold-up motors 47 and 48 comprise cylinders 49, 50 formed in the rear face of the flat valve, FIG. 4, each having a solid or closed end bridge piston 51 therein urged by fluid under pressure against the face of end head 19. The face of the bridges are provided with circumferentially extending timing slots 53, 54 arranged as hereinafter described. Drilled passages 55 connect the timing slot 53 to cylinder 49 and the timing slot 54 to cylinder 50.

The face of the flat valve and different relative positions of cylinder ports thereon are shown in FIGS. 2, 5, 6, and 7. Valve port 31 has port extensions 31a and 31b,

and valve port 32 has port extensions 32a and 32b. These port extensions are provided by tapered slots whose adjacent ends are spaced apart an amount slightly greater than the circumferential length of a cylinder port, so that a cylinder port crossing the bridge does not interconnect the valve ports. This is illustrated in FIGS. 2 and 6 which show a cylinder port 29 centered on one of the bridges without overlapping either port extension.

The timing slots 53, 54 are preferably spaced radially of the center of the bridges and of the port extensions, whereby any groove formed by wear that circumferentially extends a port extension will not interconnect with a timing slot. The circumferential length of the timing slots are each slightly less than the corresponding spacing between adjacent cylinder ports so that a timing slot is in registration with only one cylinder port at a time, as shown in FIGS. 2 and 6, for timing slots 54 and 53 respectively. Drilled holes 56 are provided at each end of the timing slots to avoid taper at the end and minimize wear. It should be noted in this arrangement that the timing slots are actually longer than the spacing between adjacent port extensions. It should also be noted that the angular rotation of the cylinder when a cylinder port is centered on a bridge without connection to either adjacent port extension is very small and is of the order of one degree of rotation. One degree of rotation is also the interval of travel provided for one cylinder port to leave a trailing end of a timing slot and a succeeding cylinder port to begin registration with the leading end of the same timing slot.

FIG. 2 shows a cylinder port 29a centered on the left bridge in registration with timing slot 53 but not in registration with either of the adjacent port extensions 31a and 32b. At the same time a pair of adjacent cylinder ports 29d and 296 are entering and leaving the right bridge, are in registration with ports 31 and 32 respectively but are not in registration with timing slot 54. In this position three cylinder ports register with each valve port and one cylinder port is centered on a bridge. FIG. 6 shows a mirror arrangement of the cylinder ports shown in FIG. 2 and is obtained upon rotation of the cylinder barrel an amount equal to one-half the angular spacing between adjacent cylinder ports.

Between the positions shown in FIGS. 2 and 6 the cylinder ports are distributed on the valve as shown in FIGS. 5 and 7. FIG. 5 shows a few degrees of rotation from that of FIG. 2, with the cylinder port 2911 that was centered on the bridge is now registering with both the timing slot 53 and port extension 3111. It also shows that cylinder port 29d is now registering with port 31 and timing slot 54. Four cylinder ports are therefore in communication with pressure supply port 31, and by means of the timing slots and cylinder ports 29a and 29d the auxiliary bridge motors are simultaneously supplied with pressure fluid from pressure port 31.

Rotation of the cylinder barrel to the position shown in FIG. 6 brings cylinder port 29a out of registration with timing slot 53 and cylinder port 29d out of registra tion with port extension 31b. Another degree of rotation of the cylinder barrel, FIG. 7, shows cylinder port 29d now registering with leading port extension 32a and cylinder port 29g registering with the timing slot 53 to thereby simultaneously connect both bridge motors to the low pressure or exhaust port 32 and simultaneously deencrgize the bridge motors. In FIG. 7 three cylinder ports register with valve port 31 and four cylinder ports register with valve port 32. Thus, for either direction of rotation of the cylinder barrel, the auxiliary motors are simultaneously energized whenever four cylinder ports are in communication with valve pressure port 31 and simultaneously deenergized whenever four cylinder ports are in communication with valve low pressure or exhaust port 32. Stated in another way in view of the mirror positions of the cylinder ports in FIGS, 2 and 6, the auxiliary motors under both bridges are simultaneously energized when a cylinder port moves from a center position on one bridge toward the pressure port, and both auxiliary bridge motors are simultaneously deenergizcd when a cylinder port moves from a center position on one bridge toward an exhaust port.

While but one embodiment of the invention has been shown and described, changes and modifications may be made therein within the scope of the claims.

I claim:

1. A hydraulic motor comprising a rotatable cylinder unit having an odd number of N pistons and cylinders arranged therein and connected to cylinder ports in a valve seat formed coaxially of said cylinder unit, a valve supported coaxially of said valve seat for axial movement on a stationary member of said motor, said valve having a pair of arcuate ports with which said cylinder ports alternately register as said cylinder unit rotates, hold-up motors in constant communication with said valve ports and effective to hold said valve balanced on said valve seat when one-half of N-l cylinder ports are connected to a pressure one of said valve ports, auxiliary hold-up motors under the bridges of said valve between said ports to provide an additional force to hold said valve balanced on said valve seat only when one-half of N +1 cylinder ports are connected to said pressure one of said valve ports, and passage means in the face of each said bridge connected to the auxiliary motors thereof and adapted to register with a cylinder port crossing said bridge, each said passage means extending circumferentially slightly less than the spacing between adjacent cylinder ports, whereby said auxiliary motors under both the bridges are simultaneously connected to said pressure one of said ports whenever one of said cylinder ports moves beyond the center of one of said bridges toward said pressure one of said valve ports and are operatively disconnected therefrom and connected to said exhaust one of said ports whenever one of said cylinder ports moves beyond the center of the other one of said bridges.

2. A hydraulic motor comprising a rotatable cylinder unit having a valve seat with a coaxial ring of N cylinder ports therein, N being an odd integer, an axially floating flat valve supported on a stationary member for engagement with said valve seat, diametrically opposite arcuate ports in said valve with which said cylinder ports alternately register upon rotation of said cylinder unit, hydraulic hold-up motors positioned in said Valve and supplied with fluid from adjacent said ports for holding said valve on said valve seat, auxiliary hold-up motors positioned in both the bridges of said valve between said ports for successive communication with said ports as said cylinder ports cross said bridges for energization thereof whenever one-half of N +1 cylinder ports communicate with said pressure one of said valve ports, and circumferentially extending timing slots in the faces of both of said bridges being connected to the auxiliary hold-up motors of their bridges and arranged so that one of said cylinder ports will interconnect one end of one of said valve ports to the timing slot in one of said bridges as another of said cylinder ports simultaneously interconnects the other end of the same one of said valve ports to the timing slot in the other one of said bridges.

3. A hydrodynamic machine comprising a rotatable cylinder unit having a valve seat with circumferentially spaced cylinder ports therein, an axially floating type fiat valve arranged with its face substantially in engagement with said seat, said valve having a circumferentially extending high pressure port and a diametrically opposite circumferentially extending low pressure port, intermediate circumferential portions defining bridges of the valve, hold-up motors under the ports of said valve to balance and hold said valve on said valve seat when the number of cylinder ports registering with said high pressure port is a minimum, auxiliary hold-up motors under both of said bridges to increase the hold-up force to balance and hold said valve on said valve seat when the number of cylinder ports registering with said high pressure port is a maximum, passages through said valve connecting said auxiliary hold-up motors to the face of said bridges, and recess means circumferentially extending said passages along the face of said bridges so that through said recess means said auxiliary hold-up motors simultaneously communicate with said pressure port via generally diametrically opposite said cylinder ports when in partial registration with said pressure port and alternately simultaneously communicate with said exhaust port via generally diametrically opposite said cylinder ports when in partial registration with said exhaust port.

4, In a hydraulic motor adapted for rotation in either direction under load and at relatively slow speeds, the combination comprising a rotatable cylinder barrel having cylinders and pistons arranged in a circle coaxially thereof and having ports in a valve seat formed on an end of said cylinder barrel, a valve non-rotatably supported on a stationary member for movement axially of said stationary member and coaxial sealing engagement withsaid valve seat, said valve having diametrically opposite arcuate pressure and exhaust ports formed therein defining bridges therebetween, said cylinder ports alternately registering with said pressure and exhaust ports as said cylinder barrel rotates, hydraulic hold-up motors distributed in said valve in accordance with the pressure field of said ports and connected to the'adjacent one of said ports, an auxiliary hold-up motor circumferentially centered in each bridge of said valve, and a circumferentially extending timing slot in the face of each bridge and connected to said auxiliary hold-up motor in said bridge, said timing slots arranged to be simultaneously connected by cylinder ports to said pressure port and alternately with said exhaust port with a time interval therebetween equivalent to a cylinder port rotation of the order of one degree.

5. A hydraulic motor comprising a rotatable cylinder unit having a coaxial valve seat with an odd number of N cylinder ports therein,'a flat valve non-rotatably supported on a stationary member for engagement with said valve seat, said flat valve having diametrically opposite arcuate supply and exhaust ports with which said cylinder ports alternately register upon rotation of said cylinder unit, hydraulic hold-up motors to hold said flat valve balanced on said valve seat against a separating force provided by a distribution of one-half of N 1 cylinder ports connected to said supply port, each radial segment of said flat valve between the arcuate ports defining a bridge, each bridge having an auxiliary hold-up motor centered on an axis between said valve ports and having a piston area substantially one-half that of one of said cylinder ports and each said auxiliary hold-up motor being connected to a timing slot formed in the valve face of the bridge, each said timing slot extending circumferentially in opposite directions to an extent slightly less than the corresponding spacing between adjacent said cylinder ports whereby the auxiliary hold-up motors of both bridges are simultaneously energized when the separating force on said valve is increased by a distribution of onehalf of N +1 cylinder ports connected to said supply port.

6. A hydraulic motor comprising a rotatable cylinder unit having cylinders and pistons therein and an end having cylinder ports and providing a valve seat, a stationary member, a flat valve non-rotatably secured to said stationary member for axial movement relative thereto and sealing engagement therewith and with said valve seat, said flat valve having arcuate supply and exhaust ports defining bridges therebetween, each of said supply and exhaust ports extended at both ends by slots tapering into the face of the bridges and defining port extensions, adjacent port extensions spaced circumferentially slightly more than circurnferential length of a cylinder port, hold-up motors in said valve urging said valve against said valve seat in accordance with the pressure in said supply and exhaust ports, auxiliary hold-up motors in the bridges connected by timing slots in the faces of the bridges and adapted to be alternately connected by a cylinder port to the supply and exhaust ports of the valve, said timing slots spaced radially of said port extensions and extending circumferentially to an extent slightly less than the corresponding circumferential spacing between adjacent edges of adjacent cylinder ports.

7. A hydrostatic machine comprising a rotatable cylinder unit having a valve seat with an odd number of cylinder ports, therein, a valve arranged with its face substantially in engagement with the valve seat, diametrically opposite high and low pressure ports in the valve with which said cylinder ports alternately register as said cylinder unit rotates, holdup motors under the ports of said valve and in constant communication with their associated ports for holding the valve balanced on the valve seat, said valve having bridges which are intermediate circumferential portions between the valve ports, auxiliary holdup motors under the bridges connected by passages to the face of the bridges, and recess means in the face of the bridges which connect with the passages to the auxiliary i holdup motors and which extend circumferentially along the face of the bridges so that the cylinder ports and the recess means cooperate to simultaneously connect the auxiliary holdup motors under both the bridges to the high pressure valve port only when a maximum number of cylinder ports register with the high pressure port and alternately to simultaneously connect the holdup motors under both the bridges to the low pressure valve port only when a minimum number of cylinder ports register with the high pressure valve port; whereby said auxiliary holdup motors assist in maintaining the valve balanced on the valve seat only when the maximum number of cylinder ports register with the high pressure valve port.

References Cited in the file of this patent UNITED STATES PATENTS 2,484,337 Ferris Oct. 11, 1949 

